Flax: growing & caring for linseed

Flax is an ancient crop that is cultivated for its plant fibres and seeds. Here is a quick introduction to the flax plant as well as tips on varieties, sowing and care.

Common flax (Linum usitatissimum) has been cultivated for thousands of years for medicine, textiles and food. Find out how to plant and successfully cultivate linseed in your own garden in this article.

Flax: origin and properties

Flax belongs to the flax family, known as Linaceae, which comprises about 90 different species. These are found worldwide, but grow particularly well in the Mediterranean region and in the south-west of the USA. Common flax originates in the eastern region of the Mediterranean, where it was already used as a medicinal plant for respiratory diseases around 5000 BC. Fossilised flax seed has also been found in various Egyptian pyramids as flax fibres were used to clothe mummies.

Flax is a delicate annual that grows 50 to 120 cm high and has lance-shaped leaves. The radial, five-petalled flaxseed flower blooms between the end of May and August. The flowers can be blue, white or, more rarely, pink. Although flax plants are mainly self-pollinating, they do also attract some types of bees. After pollination, the flowers develop round seed pods consisting of five compartments, each with two shiny, brown or golden coloured seeds. These ripen from the end of July until September, during which time the plant itself turns brown and dies. Harvest time begins when the pods turn yellow and the seeds rattle inside.

So, are flax and linseed the same thing? Well, yes and no. Flax and linseed are of the same plant species, but one or the other term is used depending on the purpose of cultivation. Flax (Linum usitatissimum convar. elongatum) is used for growing flax fibre. Here the focus is on tall, elongated, unbranched plants. Meanwhile, linseed (Linum usitatissimum convar. mediterraneum) is primarily cultivated for its many seed pods and their high oil content.

The best species and varieties

In addition to its pragmatic uses, flax species can also be a beautiful addition to your garden. Read on for an overview of some of our favourite species and varieties.

Golden Flax (Linum flavum)

Golden flax is a perennial native to central and southern Europe. As suggested by its name, the colour of its flowers range from light to golden yellow. Golden flax typically grows to about 30 cm tall, and the aboveground portion dies back in autumn. Though this species is hardy, it should be covered with brushwood or leaves to overwinter in very cold areas. With a height of 20 cm, the golden flax variety ‘Compactum‘ is a smaller alternative.

Common flax (Linum usitatissimum)

When selecting among common flax varieties, consider the purpose of use. Flax plants used for fibre usually grow much taller and produce fewer seeds. Linseed varieties develop more seeds and a greater amount of linseed oil which contains a high content of valuable omega-3 fatty acids.

Varieties for linseed and for oil

• ‘Ingot’: Variety with small, yellow seeds and tall, sturdy plants. The seeds ripen from August onwards.
• ‘Lirina’: Oil-rich and high-yielding linseed variety with blue flowers that also typically ripens beginning in August. It is somewhat prone to powdery mildew and tends to not be as stable as other varieties in heavy soil.
• ‘LS Koral’: Golden variety with light yellow seeds and high oil content. Maturity is from August to September.
• ‘Serenade’: Linseed variety with white flowers and higher seed-yield potential but lower oil content. As this variety has a medium growth height, it tends to be more stable.

Flax varieties for fibre

• ‘Avian’: Good fibre quality and high yields. Juvenile development is rather reluctant, and the plants tend to bend and break more easily in wind and bad weather than other varieties.
• ‘Felice’: High fibre yield and good disease resistance. Young plants of this variety grow slowly. Maturity is from August to September.
• ‘Lisette’: Rapid young plant development and maturity from August to September. This variety is stable, insensitive to most diseases and produces high fibre yields.

Purging flax (Linum catharticum)

Purging flax, also known as fairy flax, is a variety native to Great Britain, central Europe and Western Asia. It typically grows in rough pastures and fens. The delicate five to 25 cm tall plants produce dainty white flowers and golden seeds.

Red flax (Linum grandiflorum)

This annual flax species originates in Northern Africa. With attractive three to four centimetre large flowers, red flax grows up to 40 cm tall and makes a great addition to a bee pasture. When sown in spring, the flowering period begins as early as June and lasts until October.

• ‘Bright Eyes’: Variety with remarkably attractive white flowers with a red centre. The flowers bloom from June to October.
• ‘Rubrum’: Classic variety of red flax with large, deep-red flowers.
• ‘Salmon Bright Eyes’: Long-flowering variety with a growth height of 40 − 50 cm. The flowers are salmon pink with dark orange-red centres.

Spanish blue flax (Linum narbonense)

Spanish flax is a perennial that grows up to 40 cm high and forms a 30 cm wide cluster of light blue flowers. This frost-tolerant plant flowers between June and August.

Perennial Linseed (Linum perenne)

Perennial flax prefers sunny, dry locations on humus-sandy and stony soils. It forms numerous blue flowers in summer and, in suitable locations, reproduces by self-seeding.

• ‘Himmelszelt’: Perennial blue flax with a growth height of up to 50 cm. This variety flowers between June and August and reproduces by self-seeding.
• ‘Nanum Saphir’: Perennial variety with numerous sky-blue flowers. It grows up to 25 cm high and is compact and strongly branched.
• ‘Nanum Diamant’: Variety with compact growth up to 25 cm high and numerous white flowers.

Growing flax from seeds

The optimal location for flax is somewhere sunny and warm. As for soil conditions, deep, well-draining soil with good water retention is ideal. Sandy loam soils with a pH value between 6.2 and 7 are optimal for growing flax. The plant can be cultivated in a garden bed or as an ornamental plant in a pot on a balcony or terrace. Sow flax seeds directly into the soil between mid-April and the end of May at the latest. Plant linseeds five to 10 cm apart, leaving 20 to 30 cm between rows. That comes to about 14 to 20 g of seed per square metre. To ensure germination, sow the seeds no deeper than one to two centimetres. Germination takes place within seven to 14 days at temperatures as low as 3 °C. During germination and in the young plant phase, the seedlings should always be well supplied with water. Young plants can tolerate short springtime frosts as low as – 4 °C without damage.

Planting flax seeds at a glance

• Optimal location for flax: Sunny and warm in sandy loam soils with good water retention capacity.
• Sowing from mid-March to early April directly in soil; sowing depth: 1 − 2 cm.
• Seed spacing 5 − 10 cm, row spacing 20 − 30 cm; approx. 14 −20 g linseed per square metre.
• Germination occurs at 3 °C or above, late frost tolerant as low as -4 °C.
• Water seeds and young plants regularly and keep soil moist.

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Linseed has a relatively short growing season. On average, only 100 to 120 days pass between sowing and harvesting. Therefore, various vegetables such as spinach (Spinacia oleracea), lamb’s lettuce (Valerianella locusta) and radishes (Raphanus sativus) can be grown before and after the flax plant as pre- and post-crops. Linseed itself should only be grown in the same soil every six years. Growing flax in the same bed multiple years in a row leads to stunted growth and poor yields. Fungal diseases that attack linseed, such as Sclerotinia, Fusarium or Phytium, can survive in the soil or be transmitted from previous crops, so refrain from sowing linseed after sunflowers (Helianthus annuus) or legumes (Leguminosae) such as peas (Pisum sativum), beans (Phaseolus vulgaris) or lentils (Lens culinaris).

Did you know? Similar to cress (Lepidium sativum), linseed can be cultivated and eaten as sprouts. To do this, simply soak the seeds in cold water for a few hours and then leave them to germinate on a paper towel or in a sprouting jar or tower.

Plant care

Flax is quite easy to care for, as the plants are hardly demanding and usually thrive without special attention. However, young plants are not very competitive, so are easily overtaken by troublesome weeds. Regular weeding and hoeing of the planting rows is therefore an essential care measure until the plants have reached a height of 10 to 20 cm. As flax is not nutrient sapping, it does not require additional fertilisation when planted in normal garden soil or in nutrient-rich potting soil. In fact, giving flax too much nitrogen can cause the already tender plants to develop soft stems which are prone to bending and breaking in stormy weather. Seed quality and shelf life also deteriorate with excessive fertilisation.

After sowing flax seeds and caring for the plants’ growth, you can harvest the ripe seeds in late summer. Check out our article on harvesting and using linseed for useful tips on how to do so.